Watershed Management and Soil Erosion
Forests provide a buffer to filter water and to hold soil in place. They sustain water and soil resources through recycling nutrients. In watersheds where forests are degraded or destroyed, minimum flows decrease during the dry season, leading to drought, while peak floods and soil erosion increase during the wet season. Flooding along the Baram River in Sarawak has increased significantly since logging began, the major floods occurring in 1979 and 1981.168 Massive floods, directly linked to excessive logging, have caused hundreds of deaths in the Philippines169 and Thailand.170 Much of the current logging carried out in Sarawak and other places is on steep lands dominated by surface materials that are highly susceptible to erosion when disturbed.171 Data collected by the Malaysian Department of Environment in 90 long-term sampling site locations within 21 river basins has detected incredibly high suspended sediment loads in most rivers and tributaries. This mainly originates from upstream soil erosion caused by the indiscriminate construction of logging roads and camps, skid trails and logging itself.172 Dr Saulei of the University of Papua New Guinea also blames the logging industry for 'accelerating erosion, weathering and humus decomposition, and leading to widespread formation of soils with low nutrient and absorptive capacities'.173
Most of the destructive forest fires that have recently raged out of control across the world, from the Amazon to Indonesia, are widely acknowledged to have been either started by and/or exacerbated by logging and agricultural development companies, such as the oil palm industry. One of the most detailed studies on the effects of fires in Kalimantan, Indonesia, concludes that the considerable decrease in foliage and related changes in the stand structure, increase of albedo, and horizontal and vertical air movements caused by fires, may produce significant and lasting...
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